Base 4 Repunits
Table
Format: small prime × proven prime<size> × (probable prime)<size> × [composite]<size> × {unknown}<size>
| 227: | \[{4^{227}-1\over3}\] | 297371 × 26986333437777017<17> × 3454631579714210387<19> × 69982170658265444713117545258712031103399659<44> × 7992177738205979626491506950867720953545660121688631<52> |